Many Sites Forego Redundant Backup

Whenever a data center outage knocks a bunch of popular sites offline, users wonder why these services don't simply shift to a backup stored at another data center. If you have a copy of your content in more than one facility, you can adjust the DNS settings to roll over to the secondary site. This issue was a hot topic of discussion following the outages last year at 365 Main and Rackspace. Why didn't the popular Web 2.0 services affected by these outages - a group including Technorati, TypePad and 37Signals - have redundant backups?

They're not alone, as Rackspace indicates in its IPO filing. "While data backup services are included in our hosting services, the majority of our customers do not elect to pay the additional fees required to store their backup data offsite in a separate facility," the company reported.

Keep in mind that Rackspace offers advanced hosting services to many enterprises as well as Web 2.0 companies, and was offering offsite backups within its network as an add-on paid service. If the majority of Rackspace customers aren't storing data in more than one data center, what does the redundancy picture look like further down the value chain?